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Senior Member
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750 Posts
Discussion Starter #1
What is the normal boost? i have a 08 auto 4:10 gears stock with the latest flash from ford. I towed my flat bed 4,000 pounds empty 38 miles then came back with a geo prisem on it 1700 pounds so around 6,000 pounds for 39 miles I hand cal. the fuel milage it was 8.2 i never really used more then 1/4 of the go pedal. NOT INPRESSED one bit I guess this meens when i put my 16K 5th wheel behind me it will get 6-7 MPG. Even if i pull out unloaded and run up to 65-70 MPH i will see 28-30 psi of boost is that normal? I was seeing 35-38 when towing that 6,000 pound load does that sound right?
Love the truck But it looks like it will eat me out of house and home when it comes to fuel.
 

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Junior Member
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147 Posts
The 6.4 likes fuel! :)

I get 9-10 towing my 8k lb (empty) fiver, and that is with my F250 with 3.73 gears. Up hills loaded, it can easily see 35-38 PSI of boost. Unloaded, accelerating up hills, or on flat land aggressively, it can hit 30 PSI easy.

Drive like there is an egg between your foot and the go pedal, and it will help, but still won't be stellar.
 

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Let it all Ride
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1,316 Posts
These trucks suckass fuel economy wise. The only help is deleting. As far as your boost numbers, depending on the terrain, that sounds about right.
 

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Senior Member
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750 Posts
Discussion Starter #4
If i delete and use a mini max what can i expect to see real numbers please dont candy coat it. I tow a 40 foot 5th at 16K will i get 10MPG? on the flats?
 

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Junior Member
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124 Posts
If i delete and use a mini max what can i expect to see real numbers please dont candy coat it. I tow a 40 foot 5th at 16K will i get 10MPG? on the flats?
10mpg with 12,500 lb 5th travel trailer is about exactly what I get, running 4.30 gear. I keep it 65-68mph on cruise control just about any time I'm on the hwy whether loaded or empty. My truck will not drop a gear pulling a hill fully loaded, so boost will peg the full scale of the gauge, as others have stated.

The truck has been running Spartan setup before I ever hooked a trailer to it (43,000 miles now), so I can't comment on mpg pre-tune.
 

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Let it all Ride
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1,316 Posts
I would say 10-12 on flats is pretty reasonable. Spend depending of course.
 

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Senior Member
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750 Posts
Discussion Starter #7
10mpg with 12,500 lb 5th travel trailer is about exactly what I get, running 4.30 gear. I keep it 65-68mph on cruise control just about any time I'm on the hwy whether loaded or empty. My truck will not drop a gear pulling a hill fully loaded, so boost will peg the full scale of the gauge, as others have stated.

The truck has been running Spartan setup before I ever hooked a trailer to it (43,000 miles now), so I can't comment on mpg pre-tune.
4:30 gears at 68 must be running 24-2500 RPM right?
 

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